Titration studies with IgG anti-A antibodies revealed similar activity at both 4 and 37°C. The saline activity of IgG anti-A antibodies generally increased as the papain titre increased with both cord and adult A, and A, cells. Sera with papain titres >256 had saline titres in the range 32-256 at 37°C.Estimations of the IgG anti-A content of 'immune' anti-A sera made by titration following partial neutralization revealed a decreasing quantitation of the results with increasing saline IgG anti-A titre, as shown by comparison to the 2-ME method.

2,140 pregnant Sudanese women attending the antenatal clinic in Omdurman Maternity Hospital during the period November 1975 to December 1976 had ABO and Rh typing performed. Their sera were also screened by a modified papain enzyme technique for the presence of atypical antibodies. The rate of Rhesus immunization, the frequency distribution of blood groups, the atypical antibodies encountered, and the advantages of the method used for screening the sera in a developing country are discussed.